Molded sound-reproduction article



Apr; Hi?, R923. v EASEJSE E. E. Novo-mv MOLDED SOUND REPRODUCTION ARTICLE Filed Jan. 1, 1921 etienne nel. ia rara.

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LEDED SOUND-REPRODUCTION ARTCLE.

Application. led January 21, 1921. Serial No. 438,928.

To all 'whom it may concern:

Be it known that il, EMIL E. Novoa-Nr, a citizenrof the United States, and resident of Logan, Philadelphia, in the county of Phila- 6 delphia and State of Pennsylvania, have 1nvented certain new and useful improvements in Molded Sound-Reproduction Articles, of Which-the following is a specification.

Thisinvention relates to the manufacture 10 of articles for use in the art of sound reproduction, such as sound records and matrices, and has particular application to the utilizationof an infusible synthetic resin in molding such articles. l5 As is Well known, certain synthetic resins such as phenolic condensation products possess the characteristics of reacting under the application of heat to first assume a melted vor fusible state and then hardening or set- 2@ ting into a non-flowing or infusible condition. Such a synthetic resin in its melted or fusible condition readily lends4 itself to the molding l or fashioningof the desired article, butherctofore it has been deemed impracticable vto form an article after the synthetic resinous mass has reacted toits hard, non-melting or infusible stage, and,vtherefore, it has been y the eneral practiceto fuse or melt and then har en and set the material during the mold Se ing of an article, that is to say, in the manufacture of-a shape, the synthetic resin in its i raw or fusible state has been applied to the mold or matrix end then subjected to heat and pressure While in the matrix so that the au material would rst melt or fuse to render'it moldable, and then harden and set to give the article a permanent infusible form.

The disadvantages of this method, however, arethat the fusible material during the .so molding operation has a tendency to Aflow away from the lines of pressure, thereby pro ducing irregular and imperfect surfaces on the record. Furthermore, when the fusible material is hardened in the mold it hasta 4a tendency to stick or adhere to the latter` rendering it difficult to` strip the ymolded record from the matrix Without marring or injuring the surface thereof, particularly if these be records of the lateral groove type 5o Where the record grooves are relatively deep. Furthermore, during the reaction.ofsuch fusible resin in the molding operation ammonia,water and water gas are generated, and portions of these gases are necessarily 1ma prisoned 1n the mass, and are hable to cause 'permitted to hardenand set, as by cooling, the

blistering, distortions and warping` on the surface of the completed record. This proc-l ess on the whole is very slow and requiresl the greatest care to avold the production of imperfect records and also usually requires the use of metallic -matrices owing to the aflinity which the fusing or melting resin has for surfaces of synthetic resinous material. Consequently although a synthetic facedrnatrix is of 'greater strength and is more econonnicalthan a metallic matrix, it has been impractical heretofore te use such a synthetic resinous matrix vin lthe molding of articles from fusible materials.

lin some instances it has beenproposed torender the synthetic resin permanently thermoplastic by adding thereto a solid solvent4 of plasticity agent, so that when an article had been molded from this composition, and

76 material of such article might be subse-` quently again rendered fusible by the application of heat. But this involves the addition to the synthetic resin of a distinct ele ment, a thermo plasticity agent, which rsuited in a composition possessing centaip disadvantages.

Forexarnple such a composition also has a peculiar afiinity for and will stick to synthetic resinous matrices, due to the presence of the plasticity agent or solid solvent, and the materialloses its quite infusible nature, in that it is practically impossible to bring. it to the desired state of hardness or infusibility, so that a record made from such a permanently thermoplastic composition is easily marred or scratched by the reproducinnr needle and the playing of such a record is accompanied by continuous scratching or hissing noises.

It has also been proposed, in the manufacture of sound records toapply4 a varnish or layer of fusible synthetic resin to a matrix and then heat the coated matrix for about 18 l1ours,.at a relatively low temperature, to le@ drive off the gases Without undue bubbling or blistering, and to convert the synthetic V resin into an infusible reacted sheet. Upon this infusible facino a backing blank, usually containing a. fusible synthetic resin o r other we soft ccmentitius material has been imposed;

and heat and pressure thenfa'pplied to convert all of the synthetic yresin into an in! fusible`v condition and tol unite the backing blank with the infusible face blank, the in- .31o

tegral article being then stripped from the matrix, the latter being in the nature of a metallic disk.

This method is slow, tedious .and expensive, requires the greatest skill in practice to avoid such gassing as will result in blistering, warping and roughening of the record surface. Furthermore it requires the use of expensive metal matrices and thehmaintaiib ing of the presses and matrices in use for such an extended period as to cut down the per diem production to such an extent as to render the ultimate cost of production exceedingly expensive.

By the practice of my invention I have discovered that I may use a synthetic resinous material which has been rendered nonmelting, non-fiowing or infusible prior to the placing of the same in the matrix, and thereby I eliminate all of the disadvantages above recited and obtain certain positive and pronounced advantages. I have found that by ieducin an .infusible body of synthetic resin, in t e nature of a condensation product, to a comminuted mass, and then sub'ecti ng the same to heat and iressure, I am found b ena led to weld the particleso the mass into a homogeneous body which will faithfully' reproduce the characteristics of the matrix. I have described the action which takes place in the practice of my process as to welding of the particles, because I have experiment that there is no melting of t e material in molding, and no pronounced flow of the particles, as the mass is substantially inert. For example if heat alone is applied to the powder or infusible synthetic resin, even at a temperature far above the melting temperature of such resins, for example the application of a temperature of 423 degrees F., the resin will still maintain itspowdery Vintusible form without any sign of welding or union. the other hand if pressure alone be applied, oven to the extent of 2000 pounds to the square inch, the same result will take place andthe comminuted mass will still maintain its powdery characteristics. However, if both heat and pressure be applied at a relatively low pressure and at a relatively' low degree of temperature, the particles of the mass will weld or amalgamate into a homogeneous body. ily the use of such infusiblc material I am enabled to use strong, cheap, synthetic resinous matrices without the danger of sticking or gassing, as thc gas has already beenremoved from the rcsinous mass. The record molded from such au iii-fusible body may also be stripped bot from the l matrix, or without the necessity of cooling.

thereby greatly speeding' the process of quickly releasing the matrices for subse quent use in molding other records, thus tending to the economical production ot a great many articles. Furthermore, l 'am enabled to make use of discarded infusible synthetic resinous articles, as these may be ground up to powdery torni and employed for molding new records, thus enabling me to salvage or reclaim material which has heretotore been considered unavailable for subse uent molding purposes.

y invention consists in the improvedy sound record set forth in and falling within the scope of the appended claims.

In the accompanying drawings:

Figure l, is a view showing conventionally theplatens of a heated hydraulic press and `showing in cross section a matrix being molded against a master record.

Figure 2 is a cross sectional view of the molded matrix.

Figure 3 is a view showing the platens of the press conventionally and illustrating the molding of a double face phonograph Irecord. Figui-e4 ivs a cross sectional view of the completed double face record.'

Figures 5 and" 6 are views illustrating forms of blanks which may be used in making the matrices and the sound records.

One preferred method of practicing my invention is as follows:

I take a body of fusiblesynthetic resin, such for instance as a phenolic condensation product composed of phenol and formaldehyde; or phenol and acetaldehyde; or phenol and -furfuralg preferably employing a suitable catalyst and a hardening agent in connection with the mixture employed. This fusible body of synthetic resin I subject to heat in an oven at a suitable temperature, say about 250 degrees F.,for the desired period of time, say from 2 to 6 hours, for the purpose of baking the mass or reducin the same to a state of infusibility, while driving off all the gases of reaction, as well as any solvent or moisture that may be resent. lVhen the syntheic resin has been re ucedto estate of infusibility, it is removed from the oven and ground or comminuted ina suitable mill, for example a ball mill, to reduce it to a powdery or comminuted mass. I then referably `form a blank such as is shown in igure 5, which blank consists of a body of fibre l. having an infusible powder Vincorporated therein as shown at 2. As this infusible powder cannot be dissolved thesheet is made in this instance by., mechanically mixing the powder with the fibrel pulp, as in avl'ieating machine, and then forming the pulpy mass into sheets and drying `the same.` In lieu of this I may impregnate asheet of libre with a fusible solution of 'synthetic resin, and then subject the impregnated sheet to the action of heat in an oven to drive ofi thc solvents and causo the reaction ofthe fusible syntheticresin until it assumes its infusible, non-melting forni; Which ever method bc used theI fibre sheet l will have the fusible resin already incorporate there- 

